1. Field of the Invention
The present invention relates to a continuous process for the manufacture of an immobilized biocatalyst which is glucoamylase immobilized on an ion exchange resin. The present invention also includes processes for stabilizing and detoxifying such biocatalyst and a process for stripping and regenerating such biocatalyst.
2. Description of the Prior Art
Starch has, previously, been saccharified biocatalytically with glucoamylase supported on various types of supports. French Patent 2372653 discloses the deposition of fungal derived glucoamylase on a macroreticular styrene-divinyl benzene anionic exchange resin and the use of the resulting material to saccharify solutions of starch at 10.degree.-50.degree. C. and preferably at 40.degree. C.
The process used in this French Patent to load the glucoamylase onto the resin support, however, is a relatively inefficient batch process. Relatively large quantities of enzyme are used in this process, with less than about half of it absorbed on the resin, and with the excess enzyme being washed off and discarded. The batch enzyme loading procedure of the French Patent is also a relatively complex multi-step process that requires the use of buffering and resin filtering steps prior to the contact of the enzyme with the resin. The batch loading conditions of the French Patent process, of 12 hours at 4.degree. C., thus require a relatively long process, and which would also require the use of refrigeration conditions which are relatively expensive to maintain. The batch loading process of the French Patent also has a very low loading efficiency of about 33%, and produces biocatalysts of relatively lower activity. A further, and very serious, disadvantage of the batch loading process of the French Patent is that of the need for repeatedly washing the resin with a buffered solution and under agitation for an extended period of time after loading the enzyme thereon. This washing procedure leads to the loss of additional enzyme from the resin and results in the creation of fines due to the attrition of the resin particles.
Prior to the present invention, therefore, it was not possible to readily and efficiently provide high loadings of glycoamylase on macroreticular anionic exchange resins.
An object of the present invention, therefore, is to provide a simple, economic and efficient process for readily providing biocatalysts comprising high loadings of glycoamylase on macroreticular anionic exchange resins.
A further object of the present invention is to provide a means for readily loading such enzyme on such resins in a stable and irreversible form.
A further object of the present invention is to provide a facile process for disinfecting said biocatalysts without significantly adversely affecting the enzymatic activity thereof.
A further object of the present invention is to provide a facile process for the rapid removal from such biocatalysts of any microbial inhibitors present in the resin and/or enzyme components thereof, without significantly adversely affecting the enzymatic activity of such biocatalysts.
A still further object of the present invention is to provide a facile process for stripping and regenerating such biocatalyst when in spent form.